Telemeter system



3 s 3? a: 8 l5 April 16, 1968 Filed Nov. 16, 1964 B. L. SQSCIA TELEMETER SYSTEM 2 Sheets-Sheet 1 POWER SUPPLY FlGl INVENTOR BAMBY LAWRENCE SOSCI A Q MLW ATTORNEYS April 16,1968 B. L. SOSCIA TELEMETER SYSTEM Filed Nov. 16, 1964 2 Sheets-Sheet INVENT OR BAMBY LAWRENCE SOSCIA BY @flgwmcjm/ ATTORNEYS United States Patent Jersey Filed Nov. 16, 1964, Ser. No. 411,396 8 Claims. (Cl. 340--147) This invention relates to telemeter systems, and more particularly to telemeter systems for transmitting separate, cyclic, time duration signals over electrical conductors leading to a pair of remotely located receivers.

The object of this invention is to provide a system of the type just mentioned in which the number of separate signals which can be transmitted is greater than the number of conductors in the transmission line.

The preferred embodiment of the invention is described herein with reference to the accompanying drawings in which:

FIG. 1 is a schematic diagram of a two-function telemeter system.

FIG. 2 is a schematic diagram of a four-function telemeter system.

Referring to FIG. 1, the telemeter system includes a transmission line L, comprising the conductors 1 and 2, and is arranged to carry signals from the transmitters 3 and 3' located at the transmitting station to the receivers 4 and 4, respectively, located at a remote receiving station. The transmitters, which send cyclic, time duration signals, may take various known forms. As illustrated, transmitter 3 consists of a mechanical switch including a shaped contact 5, which is driven by a constant speed electric motor 6, and a cooperating wiper 7 which is carried by pivoted lever 8 and is arranged to move in an arcuate path (indicated by dashed line 9) along the face of the contact 5. Lever 8 is moved about the axis of its pivot 8a by a rod 11 which is positioned by a device (not shown) that responds to one of the two variables being telemetered. Each revolution of contact constitutes a signal cycle, and it will be evident from the shape of this contact that the ratio of the portions of each cycle in which the transmitter switch is conducting and nonconduct'mg depends upon the position of wiper 7 along the path 9. As the Wiper moves in opposite directions, the durations of the conducting and nonconducting portions are changed equal amounts in opposite senses. Transmitter 3' is identical to transmitter 3 and its actuating rod 11' is positioned in accordance with the other of the two variables being telemetered.

The transmitters 3 and 3' are connected in parallel across the conductors 1 and 2 by the leads 12 and 13 and 12 and 13, respectively, and these connections are provided with blocking diodes 14 and 14' which prevent current flow from conductor 1 to conductor 2 through transmitter 3 and prevent current flow in the opposite direction through transmitter 3. With this arrangement, transmitter 3 is rendered inactive, i.e., rendered incapable of sending signals, when conductor 1 is positive relative to conductor 2, and transmitter 3 i rendered inactive when the polarities of the conductors are reversed.

At the receiving station end of the transmission line L the conductors 1 and 2 are connected with switches 15 and 16 which serve selectively to connect them with the positive and negative terminals of a D.C. power supply 17. The connections to the stationary contacts of these switches are so arranged that the conductors 1 and 2 always are connected with opposite sides of the power supply 17. The movable contacts of the switches 15 and 16 are ganged together and are actuated by a solenoid 18 whose coil is connected in an energization circuit including power supply 17 and controlled by switch 19. This switch 19 is opened and closed cyclically by a repeat cycle timer 21. The timer 21 is so designed that switch 19 is open for a period of time at least twice as long as the cycle of transmitter 3, and is closed for a period of time at least twice as long as the cycle of transmitter 3'. This arrangement insures that each transmitter will remain active long enough to complete at least one uninterrupted on-oir cycle, and eliminates the need forsynchronizing the transmitters both with respect to each other and with respect to the timer 21. In the illustrated embodiment, it is assumed that the cycles of transmitters 3 and 3 are of equal duration, and that the lengths of the open and closed periods of switch 19 are equal.

The receivers 4 and 4 also may take various known forms, but, as illustrated, they are identical and correspond to the one described in US. Patent 2,145,026, granted Jan. 24, 1939. Receiver 4 includes a pointer 22 which is journalled on a shaft 23 and is moved in opposite directions toward minimum and maximum positions by a pair of arms 24 and 25 carried by the clutch plates 26 and 27, respectively. These plates are journalled on a supporting shaft 28 which is coaxial with shaft 23 and are shifted into and out of driven engagement with the back faces of bevel gears 29 and 31, respectively, by an actuating linkage 32. The linkage 32 is biased to the illustrated position, in which the clutch plates 26 and 27 are engaged and disengaged, respectively, by a tension spring 33, and is shifted to a second position in which the clutch plates 27 and 26 are engaged and disengaged, respectively, by a solenoid 34. The bevel gears 29 and 31, which also are journalled on shaft 28, mesh with a bevel pinion 35 which is driven by a synchronous motor 36. The output speed of motor 36 is so selected that the sum of the angular distances moved by arms 24 and 25 during each cycle of transmitter 3 equals the angular distance between the minimum and maximum positions of the pointer 22. It will be understood that pointer 22 is braked so that it stays in the position to which it is moved by arms 24 and 25, and that these arms are biased toward the maximum and minimum positions, respectively, of pointer 22 and assume those positions whenever the associated clutch 26 or 27 is disengaged.

The coils of the solenoids 34 and 34' in the two receivers are connected in parallel across the positive and negative terminals of D.C. power supply 17 by a circuit including the normally open switch 37. The switch 37 is actuated by a solenoid 38 whose coil is interposed in the lead connecting switch 15 with the positive terminals of the power supply 17, and therefore, is closed to complete the energization circuit for the solenoid coils 34 and 34' whenever the active transmitter 3 or 3 is conducting. The motors 36 and 36' of the two receivers are selectively connected with the AC. power lines 39 and 41 by circuits controlled by the switch 42 of the repeat cycle timer 21. The parts are so arranged that motor 36 is energized only when transmitter 3 is active and motor 36 is energized only when transmitter 3 is active.

During operation, the motors 6 and 6 of the two transmitters and the motor 21a of the repeat cycle timer 21 run continuously. When the cam 21b of repeat cycle timer 21 open-s switch 19, solenoid 18 is de-energized and switches 15 and 16 assume their illustrated positions in which conductors 1 and 2 are connected with the positive and negative terminals, respectively, of power supply 17. Thus transmitters 3 and 3' are rendered active and inactive, respectively. Simultaneously, cam 21b shifts the Wiper of switch 42 into engagement with contact 42a and thereby opens and closes the supply circuits for motors 36 and 36, respectively. This renders receiver 4 active and receiver 4' inactive. If, at this time, shaped contact 5 of transmitter 3 is in engagement with wiper 7, current will flow between the terminals of power supply 17 through a circuit including switch 15, conductor 1, lead 12, diode 14, shaped contact 5, wiper 7, lever 8, lead 13, conductor 2 and switch 1 6. Therefore, solenoid 38 will close switch 37 and complete the energization circuit for solenoids 34 and 34'. As a result, the solenoids in the two receivers 4 and 4 will shift actuating linkages 32 and 32' to the right and cause them to move clutch plates 26 and 26' out of engagement with bevel gears 29 and 29' respectively. If the arms 24 and 24 are not already in their initial positions, they will move to these positions under the action of the biasing forces acting on them as soon as clutch plates 26 and 26' are separated from the associated bevel gears 29 and 29'. Simultaneously, linkages 32 and 32' move clutch plates 27 and 27 into engagement with bevel gears 31 and 31', respectively. Since motor 36 in receiver 4 is running, arm 25 now rotates in a direction away from the observer, i.e., into the drawing. Ann 25 continues to move in this direction as long as shaped con tact 5 remains in engagement with wiper 7, and, if it overtravels pointer 22, it will move the pointer to a new, higher position. Since the motor 36' in receiver 4 is not running at this time, clutch plate 27 will not rotate arm 25.

When shaped contact 5 moves out of engagement with wiper 7, the circuit connecting the positive and negative terminals of power supply 17 is interrupted and solenoid 38 is de-energized. At this time, switch 37 opens to deenergize the receiver solenoids 34 and 34' and permits springs 33 and 33 to move the actuating linkages 32 and 32', respectively, back to their illustrated positions. Now the biasing force acting on arm 25 returns it to the minimum position of pointer 22 and bevel gear 29 commences to drive clutch plate 26 and arm 24 toward the observer, i.e., out of the drawing. Arm 24 will move in this direction as long as shaped contact 5 remains out of engagement with wiper 7. If the arm 24 overtakes pointer 22, it will move the pointer to a new, lower position. Since motor 36' in receiver 4 is still at rest, arm 24' does not move.

As stated earlier, repeat cycle timer 21 maintains switches 19 and 42 in their illustrated positions, and thus maintains transmitter 3 and receiver 4 active, throughout at least two cycles of transmitter 3. Therefore, during this interval, the coil 34 will be energized continuously at least once for a period of time equal to the duration of the ON portion of the transmitted signal and which is immediately preceded or succeeded by a period of continuous de-energization whose duration equals the duration of the OFF portion of the transmitted signal. Because of this, the point in the cycle of transmitter 3 at which timer 21 shifts switches 19 and 42, and renders the transmitter and receiver active, is immaterial. In other words, it is not nece sary that the cycles of transmitter 3 and timer 21 be synchronized.

After transmitter 3 has completed at least two cycles, repeat cycle timer 21 will close switch 19 and shift the wiper of switch 42 into engagement with contact 42b. Closure of switch 19 completes the energization circuit for solenoid 18 and causes it to shift switches 15 and 1 6 to positions in which they connect conductors 1 and 2 with the negative and positive terminals, respectively, of power supply 17. Therefore, at this time, transmitter 3 is rendered active and transmitter 3 is rendered inactive. Shifting of the wiper of switch 42 onto contact 4212 opens and closes the supply circuits for motors 36 and 36', respectively, so receiver 4' now becomes active and receiver 4 becomes inactive. Since the solenoid 38 closes and opens switch 37 during the conducting and nonconducting portions, respectively, of the cycle of transmitter 3', pointer 22' of receiver 4' is positioned in accordance with the transmitted signal in the same way as pointer 22 of receiver 4 during the preceding transmission cycle.

FIG. 2 illustrates the manner in which the telemeter system can be expanded to handle four separate signals.

In addition to the components of the FIG. 1 embodiment, the modified system includes the transmitters 3 and 3" and their receivers 4" and 4", a second power supply 17a and relay 37a, 38a, 21 second pair of transfer switches 15a and 16a and a third transmission line conductor 1a. The connections to the transmitters and receivers are such that transmitters 3 and 3 and receivers 4 and 4" are rendered active on one half cycle of timer 21, and the remaining transmitters and receivers are rendered active on the other half cycle of the timer. Furthermore, it will be observed that like terminals of the power supplies 17 and 17a always are connected with common conductor 2, and that, therefore, the power supplies will be connected in series opposing relation whenever both of the active transmitters are conducting. In this type of circuit, the potential across each conductor will never exceed the voltage of a single power supply. This feature is particularly important in cases where the transmission line is leased from a telephone company. Of course, in cases where higher voltages can be tolerated, a circuit which affords a series aiding connection of the power supplies can be used.

When the switches 19 and 42 are in their illustrated positions, the motors 36 and 36" in receivers 4 and 4", respectively, will be running, and the transfer switches 15, 16, 15a and 16a assume their illustrated positions. If transmitters 3 and 3" are conducting and nonconducting, respectively, current will flow from the positive to the negative terminal of power supply 17 through a circuit including switch 16, conductor 2, lead 13, diode 14, the .witch in transmitter 3, lead 12, conductor 1 and switch 15. This flow of current will energize solenoid 38 and cause it to control receiver 4 in the manner described above. At this time, switch 37a is open, so solenoid 34" of receiver 4" is de-energized and the pointer of this receiver is positioned in accordance with the OFF portion of the cycle of transmitter 3". On the other hand, if transmitter 33" is conducting and transmitter 3 is not, the positive and negative terminals of power supply 17a are interconnected by an external circuit including switch 15a, conductor 2, lead 13", diode 14", the switch in transmitter 3, lead 12", conductor 1a, and switch 16a. Current flow through this circuit energizes solenoid 38a and causes it to control active receiver 4- in accordance with the ON portion of the cycle of transmitter 3". Since switch 37 is now open, the pointer of receiver 4 is positioned in accordance with the OFF portion of the cycle of transmitter 3.

A third condition of operation is presented when both of the transmitters 3 and 3 are conducting. In this case, the power supplies 17 and 17a are connected in series opposition with each other and current will flow through both of the external circuits just described. This results in energization of both of the solenoids 38 and 38a, so the pointer of each of the receivers 4 and 4" will now be positioned in accordance with the ON portion of the signal cycle of the associated transmitter.

The timer 21 in the FIG. 2 embodiment holds switches 19 and 42 in their illustrated positions, and thus maintains transmitters 3 and 3" and receivers 4 and 4" active, for at least two cycles of the transmitter having the longer cycle. At the end of this period, the timer 21 closes switch 19 and shifts the wiper of switch 42 into engagement with contact 42b. Shifting of switch 42 stops receiver motors 36 and 36" and starts receiver motors 36' and 36", and closing of switch 19 energizes solenoid 18 and causes it to move the transfer switches 15, 16, 15a and 16a to positions in which the polarities of conductors 1, 2 and 1a are reversed. Now transmitters 3' and 3" and receivers 4' and 4" are active. An inspection of the FIG. 2 schematic will show that under these conditions, solenoids 38 and 38a will be energized whenever transmitters 3 and 3", respectively, are conducting, and that both solenoids will be energized when both transmitters are conducting. Therefore, during this half of the cycle of timer 21, the receivers are controlled by their associated transmitters in the same way as in the first half of the timer cycle.

While the preceding discussion should make evident the essential features of the improved telemeter system, there are several aspects of the illustrated embodiments which perhaps merit additional comment. First, although it is assumed herein that each signal cycle of the transmitters has both a conducting, or ON portion, and a nonconducting, or OFF portion, it should be realized that, depending on the design of the shaped contacts, the limits of the ratio of the durations of the two portions of each cycle may or may not include zero and infinity. Second, it should be understood that while the receivers employed in the illustrated embodiments utilize both the conducting and nonconducting portions of each signal cycle, the invention includes systems employing receivers that operate solely on one or the other of those portions of the cycle. Third, while the drawings indicate that all of the conductors in the transmission line L are wires, it will be obvious to those skilled in the art that one of the wires in each transmission line can be eliminted if its terminal points at the transmitting and receiving stations are grounded. In other words, one of the conductors in the transmission line of this invention may be ground. Finally, it should be apparent from a consideration of the two illustrated embodiments, that the technique used to expand the two-signal embodiment to the four-signal embodiment can be applied repeatedly to further extend the signal-handling capability of the system.

As stated previously, the drawing and description relate only to the preferred embodiment of the invention. Since changes can be made in the structure of this embodiment without departing from the inventive concept, the following claims should provide the sole measure of the scope of the invention.

What I claim is:

1. A telemeter system including (a) a transmission line, including first and second electrical conductors, leading from a transmitting station to a remotely located receiving station;

(b) first and second electrical signal transmitters located at the transmitting station and connected with said conductors, each transmitter being capable of sending cyclic, time duration signals;

(c) means responsive to the relative polarities. of the two conductors for preventing the first transmitter from sending signals along the conductors when the first conductor is positive relative to the second conductor and for preventing the second transmitter from sending signals along the conductors when the second conductor is positive relative to the first conductor;

(d) a source of direct current located at the receiving station and having positive and negative terminals;

(e) switching means for selectively connecting the terminals of the source with said conductors and having a first condition in which the positive and negative terminals are connected with the first and second conductors, respectively, and a second condition in which the connections between the terminals and the conductors are reversed;

(f) timing means for changing the condition of the switching means in cycles related to the cycles of the transmitter signals;

(g) a pair of electrical signal receivers located at the receiving station; and

(h) means at the receiving station effective when the first transmitter is sending a signal along said conductors for causing only the first receiver to operate in response to said signal, and effective when the second transmitter is sending a signal along said conductors for causing only the second receiver to operate in response to said signal.

2. A telemeter system including (a) a transmission line, including first and second electrical conductors, leading from a transmitting station to a remotely located receiving station;

(b) first and second electrical signal transmitters located at the transmitting station, each transmitter including a current flow-controlling device capable of being conductive and nonconductive, and means for changing the current flow-controlling condition of said device in uniform cycles in each of which the durations of the conductive and nonconductive portions may be varied in reverse senses;

(c) means connecting the current flow-controlling devices in parallel across the conductors and including one-way current flow means for preventing current flow from the first to the second conductor through the first current flow-controlling device and for preventing current fiow from the second to the first conductor through the second current fiowcontrolling device;

(d) a source of direct current located at the receiving station and having positive and negative terminals;

(e) switching means for selectively connecting the terminals of the source with said conductors and having a first condition in which the positive and negative terminals are connected with the first and second conductors, respectively, and a second condition in which the connections between the terminals and the conductors are reversed;

(f) timing means for changing the condition of the switching means in cycles related to the cycles of the current flow-controlling devices of the transmitters;

(g) a pair of electrical signal receivers located at the receiving station; and

(h) means at the receiving station etfective when current is flowing through the flow-controlling device of the first transmitter for activating only one receiver and controlling it in accordance with the duration of at least one of the portions of the cycle of the first transmitter, and effective when current is flowing through the flow-controlling device of the second transmitter for activating only the other receiver and controlling it in accordance with the duration of at least one of the portions of the cycle of the second transmitter.

3. A telemeter system including (a) a transmission line, including first and second electrical conductors, leading from a transmitting station to a remotely located receiving station;

(b) first and second electrical signal transmitters located at the transmitting station, each transmitter including a current flow-controlling device capable of being conductive and nonconductive, and means for changing the current flow-controlling condition of said device in uniform cycles in each of which the durations of the conductive and nonconductive portions may be varied in reverse senses;

(c) means connecting the current flow-controlling devices in parallel across the conductors and including one-way current flow means for preventing current flow from the first to the second conductor through the first current flow-controlling device and for preventing current iiow from the second to first conductor through the second current flow-controlling device;

(d) a source of direct current located at the receiving station and having positive and negative terminals;

(e) switching means for selectively connecting the terminals of the source with the said conductors and having a first condition in which the positive and negative terminals are connected with the first and second conductors, respectively, and a second conditron in which the connections between the terminals and the conductors are reversed;

(f) timing means for changing the condition of the switching means in cycles related to the cycles of the current flow-controlling devices of the transmitters;

(g) a pair of electrical signal receivers located at the receiving station, each receiver including electric motor means which when energized and de-energized causes the receiver to be active and inactive, respectively, and control means which when energized and de-energized causes the receiver to operate in opposite senses;

(h) means controlled by the timing means for energizing only the motor means of one receiver when the switching means is in its first condition and for energizing only the motor means of the other receiver when the switching means is in its second condition;

(i) an electrical control circuit for energizing the control means of both receivers and including a switching means for opening and closing the circuit; and

(j) means responsive to the flow of current through said conductors for actuating the switching means of the control circuit.

4. A telemeter system including (a) a transmission line, including first and second electrical conductors, leading from a transmitting station to a remotely located receiving station;

(b) first and second electrical signal transmitters located at the transmitting station, each transmitter including a switch, motor means for opening and closing the switch in uniform cycles, and means for varying in reverse senses the durations of the open and closed portions of each cycle;

() means connecting the switches of the transmitters in parallel across the conductors and including oneway current'flow means for preventing current flow from the first to the second conductor through the switch of the first transmitter and for preventing current flow from the second to the first conductor through the switch of the second transmitter;

(d) a source of direct current located at the receiving station and having positive and negative terminals;

(e) switching means for selectively connecting the terminals of the source with said conductors and having a first condition in which the positive and negative terminals are connected with the first and second conductors, respectively, and a second condition in which the connections between the terminals and the conductors are reversed;

(f) timing means for changing the condition of the switching means in cycles related to the cycles of the current flow-controlling devices of the transmitters;

(g) a pair of electrical signal receivers located at the receiving station, each receiver including electric motor means which when energized and de-energized causes the receiver to be active and inactive, respectively, and control means which when energized and de-energized causes the receiver to operate in opposite senses;

(h) means controlled by the timing means for energizing only the motor means of one receiver when the switching means is in its first condition and for energizing only the motor means of the other receiver when the switching means is in its second position;

(i) an electrical control circuit for energizing the control means of both receivers and including a switching means for opening and closing the circuit; and

(j) means responisve to the flow of current through said conductors for causing the switching means of the control circuit to close that circuit when current is flowing through the conductors and to open that circuit when no curernt is flowing through the conductors.

S. A telemeter system as claimed in claim 1 in which the timing means maintains the switching means in its first condition throughout at least two cycles of the second transmitter, and maintains the switching means in its second condition throughout at least two cycles of the first transmitter.

6. A telemeter system as claimed in claim 2 in which the timing means maintains the switching means in its first condition throughout at least two cycles of the second transmitter, and maintains the switching means in its second condition throughout at least two cycles of the first transmitter.

7. A telemeter system as claimed in claim 3 in which the timing means maintains the switching'means in its first condition throughout at least two cycles of the second transmitter, and maintains the switching means in its second condition throughout at least two cycles of the first transmitter.

8. A telemeter system as claimed in claim 4 in which the timing means maintains the switching means in its first condition throughout at least two cycles of the second transmitter, and maintains the switching means in its second condition throughout at least two cycles of the first transmitter.

References Cited UNITED STATES PATENTS 2,061,410 11/1936 Stablein 340-183 2,962,702 11/1960 Derr et al. 340- XR JOHN W. CALDWELL, Primary Examiner.

D. YUSKO, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,378,816 April 16, 1968 Bamby Lawrence Soscia It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

In the heading to the printed specification, lines 4 and 5, for "a corporation of New Jersey" read a corporation of New York Signed and sealed this 3rd day of June 1969.

(SEAL) Attest: M Z

Edward M. Fletcher, Jr. Attesting Officer Commissioner of Patents 

1. A TELEMETER SYSTEM INCLUDING (A) A TRANSMISSION LINE, INCLUDING FIRST AND SECOND ELECTRICAL CONDUCTORS, LEADING FROM A TRANSMITTING STATION TO A REMOTELY LOCATED RECEIVING STATION; (B) FIRST AND SECOND ELECTRICAL SIGNAL TRANSMITTERS LOCATED AT THE TRANSMITTING STATION AND CONNECTED WITH SAID CONDUCTORS, EACH TRANSMITTER BEING CAPABLE OF SENDING CYCLIC, TIME DURATION SIGNALS; (C) MEANS RESPONSIVE TO THE RELATIVE POLARITIES OF THE TWO CONDUCTORS FOR PREVENTING THE FIRST TRANSMITTER FROM SENDING SIGNALS ALONG THE CONDUCTORS WHEN THE FIRST CONDUCTOR IS POSITIVE RELATIVE TO THE SECOND CONDUCTOR AND FOR PREVENTING THE SECOND TRANSMITTER FROM SENDING SIGNALS ALONG THE CONDUCTORS WHEN THE SECOND CONDUCTOR IS POSITIVE RELATIVE TO THE FIRST CONDUCTOR; (D) A SOURCE OF DIRECT CURRENT LOCATED AT THE RECEIVING STATION AND HAVING POSITIVE AND NEGATIVE TERMINALS; (E) SWITCHING MEANS FOR SELECTIVELY CONNECTING THE TERMINALS OF THE SOURCE WITH SAID CONDUCTORS AND HAVING A FIRST CONDITION IN WHICH THE POSITIVE AND NEGATIVE TERMINALS ARE CONNECTED WITH THE FIRST AND SECOND CONDUCTORS, RESPECTIVELY, AND A SECOND CONDITION IN WHICH THE CONNECTIONS BETWEEN THE TERMINALS AND THE CONDUCTORS ARE REVERSED; (F) TIMING MEANS FOR CHANGING THE CONDITION OF THE SWITCHING MEANS IN CYCLES RELATED TO THE CYCLES OF THE TRANSMITTER SIGNALS; (G) A PAIR OF ELECTRICAL SIGNAL RECEIVERS LOCATED AT THE RECEIVING STATION; AND (H) MEANS AT THE RECEIVING STATION EFFECTIVE WHEN THE FIRST TRANSMITTER IS SENDING A SIGNAL ALONG SAID CONDUCTORS FOR CAUSING ONLY THE FIRST RECEIVER TO OPERATE IN RESPONSE TO SAID SIGNAL, AND EFFECTIVE WHEN THE SECOND TRANSMITTER IS SENDING A SIGNAL ALONG SAID CONDUCTORS FOR CAUSING ONLY THE SECOND RECEIVER TO OPERATE IN RESPONSE TO SAID SIGNAL. 